Synonyms for Subsidence (same or very similar meaning)
WordNet sense 1 (an abatement in intensity or degree (as in the manifestations of a disease)):
remission, remittal
WordNet sense 2 (a gradual sinking to a lower level):
settling, subsiding
WordNet sense 3 (the sudden collapse of something into a hollow beneath it):
cave in
From the ODE community, based on WordNet
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